SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '531a7344aae3cf94e7d7250e3975af77ce470f57d3aa9a0f34d2386c8ff8c23b' 
  AND token = '4NSIgo7GQ7oLJ2/Vtl9N6rWibplbtnwZuIMyOgmuOQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}